Testing System for the Mechanical Properties of Small-Scale Specimens Based on 3D Microscopic Digital Image Correlation

Abstract

The testing of the mechanical properties of materials on a small scale is difficult because of the small specimen size and the difficulty of measuring the full-field strain. To tackle this problem, a testing system for investigating the mechanical properties of small-scale specimens based on the three-dimensional (3D) microscopic digital image correlation (DIC) combined with a micro tensile machine is proposed. Firstly, the testing system is described in detail, including the design of the micro tensile machine and the 3D microscopic DIC method. Then, the effects of different shape functions on the matching accuracy obtained by the inverse compositional Gauss–Newton (IC-GN) algorithm are investigated and the numerical experiment results verify that the error due to under matched shape functions is far larger than that of overmatched shape functions. The reprojection error is shown to be smaller than before when employing the modified iteratively weighted radial alignment constraint method. Both displacement and uniaxial measurements were performed to demonstrate the 3D microscopic DIC method and the testing system built. The experimental results confirm that the testing system built can accurately measure the full-field strain and mechanical properties of small-scale specimens.

Portable universal tensile testing machine for studying mechanical properties of superelastic biomaterials

“…The horizontal sample allows using the microscope on a standard stand without additional brackets or consoles, opposite to vertical stationary universal tensile testing machines [16,21,26]. This sample arrangement allows maintaining the device's compactness, versatility, and portability.…”

“…To characterize the mechanical properties of thin wires and knitted meshes made from NiTi alloys, measuring equipment is required to accurately capture the superelastic behavior of the material during monotonic and cyclic tests at different tensile strain rates [9][10][11]. At the same time, the hardware must meet modern digital control requirements with the ability to display data in real-time during the test, along with saving and processing obtained data [12][13][14][15][16][17].…”

The Cold Angular Rolling Process of Copper Sheets: Unraveling Plastic Deformation Behavior and Unveiling Microstructural Transformations

“…[22][23][24] To this end, MTT data have been validated to represent the strength and ductility of bulk materials [18,21,22,25] at different strain rates. [19] By contrast, large errors appear when measuring Young's modulus [24,26] due to the effect of concurrent deformation of grips of the sample and tensile machine parts. [27,28] For acquiring the data with high accuracy, the digital image correlation (DIC) method, which has been developed for the determination of deformation by computing strains and displacements on the sample surfaces, [29,30] has been applied for MTT as a technique for noncontact strain measurement.…”